Starting sheet for electrolytic separation of nickel



STARTING SHEET FOR ELECTROLYTIC SEPARATION OF NICKEL Filed Oct. 1, 1948Dec. 18, 1951 w. J. COOK ETAL 2 SHEETSSHEET l HIWHHHHHWWWW mmmunmm Rx ymm w m a F mfaw N a.

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51 ET AL TARTING SHEET FOR EL T OLYTIC SEPARATION OF Filed 0 SHEET 2operational difiiculties.

Patented Dec. 18, 1951 STARTING SHEET FOR ELECTROLYTIC SEPARATION OFNICKEL Wilfred James Cook and Joseph Howard Tuck, Port Colborne,Ontario, Canada, assignors to The International Nickel Company, Inc.,New York, N. Y., a corporation of Delaware Application October 1, 1948,Serial No. 52,302 In Canada June 12, 1948 1 Claim;

The present invention relates to the art of producing electrolyticnickel, and, more particularly, to the production of starting sheetsused as cathodes in the conventional process of nickel electrorefining.In conventional practice, starting sheets have been produced by theplating of a thin sheet of substantially pure nickel on a mother plateof stainless steel or other suitably inert metal, such as anickel-chromium alloy, stripping the starting sheet therefrom, and thenmanually straightening the stripped starting sheet prior to its use asthe cathode in the electrolytic refining process; As thus produced, thestarting sheets are in the form of plain blanks or flat sheets which, byreason of their size, relative thinness and lack of rigidity result introublesome and expensive The inherent tendency of the cathode sheets isto warp or curl after a relatively short period in the refining bathmaking it necessary to remove the sheets from the bath and torestraighten them before continuing the growth of the cathodes. Suchwarping of thecathode sheets if allowed to progress would result inshort circuiting between the cathodes and anodes causing current losses,diaphragm failures and interruption to the process.

The initial straightening of the starting-sheets as manually performedis objectional under industrial conditions because careless operatorseither do not properly straighten the sheets or, as commonlyexperienced, dirty the face of the sheets leading to undesirable surfaceeffects on the face of the finished cathode known as honeycombing and/orberrying. The manual straightening is moreover costly andlaborconsuming. The further requirement of restraightening encountersstill greater objections and difiiculties incident to the nature of theoperation. This necessitates removal of the oathode sheets from the bathwith the coincidental quently leads to cathode-anode short circuits withthe resulting loss of current. The attempted soof the metal.

In accordance with the present invention, the objections anddisadvantages incident to the warping of the starting sheets have to alarge degree been eliminated by the provision of novel starting sheetswith special structural arrangements to provide stiffening deformationsof the metal in a special pattern, designed to reinforce or stiffen themetal against bending 0r warping in all directions, and of a characterpermissible of successful use in practical electrolytic nickel refining.Important features which'materially contribute to the successful use inthe specific process comprises an improved starting sheet havingstiffening deformations wherein the major surface areas of the startingsheets are plane or fiat surfaces and wherein the deformations of themetal provide elongated channels or ribs of shallow cross-sectional formand in an arrangement of the ribs providing maximum stiffening effectwith a minimum deformation of the metal or sheets.

It is an object of the invention to provide stiffening of the startingsheets in such manner as to maintain a straight sheet during the electrolytic separation and to provide the channel-rib formation by reverselyoffsetting the sheet ma terial to balance or neutralize the Warpingtendencies incident to nickel deposition in the process ofelectro-refining.

A further object of the invention is to produce an improved startingsheet inherently stiffened in its structural formation, wherein themajor portion of its surface area will constitute a plane or flattenedsurfacawherein the stiffening ribs are made by offsetting the metal andwherein the rib formations are of relatively shallow crosssectionalcontour suitable to economic commercial production of the novel nickelstart ng sheets.

Another important object of the invention. involvin-g the elimination ofthe detrimental features of the prior art, is to provide a startingsheet of perfected structure which shall be inherdeposited sheet nickelfrom the blank.

' which are likewise accompanied by advantages such as the maintenanceof clean contacts, re"- sulting in uniformity of voltage with highampere efficiency. 7 i

The invention likewise contemplates an improved method of producing thestarting sheets of the character described wherein the initiallystripped sheets are first roller-straightenedand subsequentlydie-pressed to form, thereby insur- 5 ing uniform production ofinherently stiffened starting sheets which will maintain theirstraightened condition throughout the practical refining process. I

Moreover, the invention provides a process for the production of aninherently rigid starting sheet involving associated steps in anelectrolytic nickel refining operation.

Other desirable features and advantages of the present invention will bemore fully understood by reference to the accompanying drawings in whichFig. 1 illustrates a plan view of a rectangular starting sheet"embodying the features of the present invention;

Fig. 2 is a vertical and longitudinal sectional View thereof taken online 2 -2 of Fig. 1;

Fig. 3 is a transverse sectional View thereof taken on line 3-3 of Fig.l

Fig. 4 depicts a sectional 'view illustrating a portion of the diestructure employed in the production of the starting sheets andillustrating in section a portion of the starting sheet corresponding toa section taken on line ii-fi of'Fig. 1;

Fig. 5 is a similar sectional view 'of a portion of the mating diesemployed in the 'ofifsetti'ngof the metal of the starting sheets whereinthe starting sheet portion illustrated in section is that portion asindicated by the sectional line 5'-'5of Fig. 1;

Fig. 6 shows a corresponding view illustrating the production of theportion of the sheet corresponding to the sectional line 6-6 of Fig. l,and

Fig.- 7 is a similar view of a die formation of modified structure.

In the "embodiment of the invention-illustrated in the drawings, theseveral features 'are incorporated in a cathode starting sheetformedas-a rectangular blank or sheet of nickel. 'The ;-rectangularblank or sheet of nickel in its initial stage is produced as a planesheet by theelectrodeposition of substantially pure nickel upon .a blankof stainless steel and by 'stripping'of'the The sheets as thusprodu'cedmay, if desired be roller ieveiea 'or initially straightenedand are then, in accordance with the invention, die-pressed'forlocalized deformation or 'off'settingof portions of the sheet nickel toprovide stiffenin'gor reinforcing ribs or channels in an arrangementsuch as to S tifie n the Starting sheetagamst bending in all directions.The arrangement is such that the number and dimensions of thedeformations are such that the major surface areaof the starting sheetis a'plane or flat surface and the stiffening deformations are such thatthe sheet is of unchanged thickness throughout. The deformations asshown in the drawings are int'heircrosssectional contour of shallowepth-ahdre auve- 1y large radius and curvature thereby to provide on oneside of the sheet a shallow curve or curved channel and at the oppositeside of the sheet an arching or rib formation of substantiallycorresponding radius. These rib-channel stiffening deformations by;reason of their "shallow depth are "of a form adapted for their economicproduction by die-pressing of the relatively high modulus of elasticitymetal. Moreover, by reason of the shallow depth of the deformationswithrelation to their width the stiffening effect is provided withavoidance of high spots or ribs of anature tending to build up or berryduring electrodeposition in such manner as to interfere with therefining process.

InFig. 1 of the drawing there is illustrated a preferred. spacing andarrangement of the stiffening deformations formed by die-pressoffsetting of the metal. This spacing and arrangement in a rectangularsheet I, comprises diagonally stiffened means, such as deformations 2and 3. Between saiddiagonal deformations is a plurality of ribs ordeformations 4 and 5 which are parallel to the longitudinal edges of thesheet. A plurality of transverse ribs or deformations 6 and I arearranged perpendicular thereto and parallel to the shorter edges of thesheet. The said ribs and deformations are formedby offsetting them toone side of the sheet. 'Associated with the longitudinal ribs is a pa'irof similarreinforcing rib-channels-or deformations '8 which are offsetto the opposite side of the sheet and which arearranged within anintermediate area thereof and parallel to an associated longitudinaledge. Similarly, reinforcing rib-channels or "deformations '9 arearranged within an intermedi- "ate area of theshe'et and parallel to thetransverse or shorter edge thereof. These reinforcing rib-channels 'ordeformations are designed to neutralize warping tendencies as may occurat certain periods'of the building up of the cathode duringelectrodeposition.

The starting sheets "may have any appropriate size, say about '29", x39", with the curved or arched deformations having a limited orrestricted depth'and width ;of say about 1 6 and about 1 respectively.'-Ihe ratio of width to depth of the deformation has been'found to besomewhat critical and is preferably of the order of 16 to -l.No-velstarting sheets embodying these deformations ---have undercomparative test with the customarily employed plain or straightstartihg sheets, shown-marked superiority in the resulting productwithout restraightening even though these -c'o'nventio'n'al straightsheets were lifted and re-straightened within twenty-four hours. 7

The spacing arrangement-of the deformations used by the inventionprovides-for the majorsurface area of the sheets to be plain'fla-t-'surfaces and further providesa marginal fiat surface 'of sufficientarea "to permit the "attachment *of the usual teririinal straps employedfor suspending the sheets in the tanks- The flat marginal portions are,accordingly, of a character to insure 'goodelectli'ca1 contact with lthe straps whichare customarily securedby spot "welds. The-startingslieetsmay normally have a *thicknessof about 0.040inch.

'In Figs. 4 to 6 'a suitable arrangement illustrated for die pressingthe starting sheets to in- *cdrporate 1therein'the stiffeningdeformationsor ribs in accordance with the present invention.

Upper "and lower-mating'dies 4'0 and 'l I are -emipley'ed and-providedwith die inserts 1'2 and 13 having theinactive or-forming surfaces'conforming to the configuration to be produced. In practice it has beenfound beneficial, at times preliminary to the die-pressing of thedefamations, to subject the stripped sheets to a roller straighteningoperation after which the sheets are die-pressed with a simultaneoustrimming or shearing of the sheets to proper size. The rollerstraightening is found to be advantageous particularly with sheetshaving low ductility which in view of the springiness of the metal doesnot readily straighten under the press. The roll straightening isdesirably performed with a single pass but may necessitate repeatedpasses with a turning of the sheet end for end or lengthwise rolling inreverse directions.

In Fig. '7 a modified die structure is shown wherein the upper dieinsert is formed as a clearance die and wherein the offsetting iseffected entirely by the lower cooperating die insert.

The preparation of the starting sheets of the unique structural formresults in substantial operational and maintenance economies,particularly as related to the elimination of the requirement forre-straightening of the sheets during the process and the detrimentalconditions incident thereto.

While a preferred formation of the novel starting sheets and an improvedmethod of production suited for nickel refining is described and shown,it will be understood that variations and modifications thereof may beresorted to without departing from the scope of the invention as definedin the appended claim. For instance, while the present improvements aredesigned particularly for meeting the more severe conditions imposed innickel refining, it will be understood that certain features thereof maybe advantageously employed in the electrolytic separation of othermetals which may offer less in difficulties such as to provide for theeconomic formation of stiffened starting sheets. Also, the rollstraighten- 6 ing' operation, as hereinbefore described, may be modifiedby first straightening of the sheet through a roll pass and thenrepeating with a rotation of the sheet through a angle instead of theangle as hereinbefore referred to.

We claim:

As an article of manufacture, a rectangular nickel cathode startingsheet for electrolytic refining of nickel having its major areaconstituted of plane surfaces disposed in a common plane and havingelongated stiffening deformations formed by shallow offsetting of themetal with :an arched cross-sectional contour, wherein the deformationshave a ratio of width to depth of about sixteen to one, saiddeformations including multiple spaced deformations at each side of thecentral axis of the sheet and extending parallel to the side edges ofthe sheet and spaced from the edges thereof by plane surface marginalareas and centered deformations extending diagonally of the sheet andincluding a continuous deformation coextensive therewith, and certain ofthe deformations being offset to the opposite side of the sheet fromother of the deformations.

WILFRED JAMES COOK. JOSEPH HOWARD TUCK.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 964,121 Rose July 12, 19101,128,676 Garber et al. Feb. 16, 1915 1,574,055 Pedersen Feb. 23, 19261,754,125 Smith Apr. 8, 1930 1,836,368 Eppensteiner et a1. Dec. 15, 19312,325,660 Chamberlain Aug. 3, 1943 2,421,582 Shepard et a1. June 3, 1947

